Effect of extracellular ice nucleation protein and cellulose on the nucleation temperature of supercooled liquid
Date Issued
2011
Date
2011
Author(s)
Hung, Hsiang-Chia
Abstract
Ice nucleation active (INA) bacteria are known to be the most active ice nucleator (IN) found in nature to date. However, nearly all INA bacteria are plant-pathogenic or enterobacteriaceae, thus direct applications to food industry are limited. In this research, we utilize extracellular ice nucleator protein (ECIN) as an IN and immobilize it onto a polyethylene (PE) film by employing layer by layer deposition method to minimize direct contact with foods. In addition, we explore the possibility of media-milled cellulose as a replacer of ECIN.
Coating ECIN on PE film resulted in freezing of 20% sucrose solution at -8℃, which does not freeze at normal conditions, and reduced 47.2% total freezing time of milk (from 94.6 min to 49.9 min). This film also can reduce the deterioration of fish actomyosin (AM) caused by freeze-thaw cycles during storage. The retention values for the three freeze-thaw cycles were greatly improved from 38%, 21%, 19% to 55%, 33%, 31%.
The nucleation temperature of pure water was raised from -21.7℃ to -16.6℃ while cellulose was add. The addition of 5 min media-milled cellulose further raise the nucleation temperature to -13.0℃. Nevertheless, increasing milling did not further raise the nucleation temperature. For examples, 90 min milling resulted in smaller particle size (1.4 μm), but a nucleation temperature at -16.1℃.
Our data show that ECIN can reduce the degree of supercooling, total freezing time and preserve the quality of AM even being immobilized onto PE film. Nevertheless, ECIN still have the possible to contact into foods. So, cellulose have the possibility as a replacer of ECIN.
Subjects
Extracellular ice nucleation protein
Cellulose
Media milling
Layer-by-layer deposition
Energy saving
Type
thesis
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